A tense truce between Syrian rebels and a Kurdish militia held Tuesday in the city of Ras al Ayn, fast against the border with Turkey. But neither side hid its disdain for the other, and both continued to hold prisoners in a standoff that suggests rebel hopes to push their control further east faces an all but certain challenge.

Ras al Ayn fell to the rebels almost two weeks ago, the first rebel victory in the country’s predominantly Kurdish northeast. But that did not end fighting here. At least five members of a Kurdish political party, the United Democratic Party, known locally as the PYD, were killed last week when they exchanged fire with the rebels, whom the Kurds asked to leave. Kurds make up about 10 percent of Syria’s population but are a majority in Hasaka province, where Ras al Ayn is located.

With the rebels saying they intend to move from Ras al Ayn east to the city of Qamishli, PYD’s militia on Monday set up 10 checkpoints between Ras al Ayn and the largely Kurdish city of Dar Basiyeh, about 40 miles to the east.

Khabad Ibrahim, one of the militia’s commanders, said that the group would allow some rebel fighters to pass but that members of Islamist groups who have been at the forefront of recent rebel victories would be kept back. He referred to them as “al Qaida” – a distinction that became clearer during the fight for Ras al Ayn.

The rebels in Ras al Ayn largely fall into two camps: those who call themselves the Free Syrian Army and operate under the nominal command of military councils that have been set up in each of the country’s 14 provinces, generally under the leadership of a defected Syrian army officer; and the mujahedeen, as they call themselves, who are members of conservative Islamist groups who espouse a post-Assad Syria characterized by Islamic Shariah law.

In Ras al Ayn, the two groups worked in a pattern that repeats itself across the country – the mujahedeen do the heaviest fighting and make up the majority of frontline soldiers, while the military councils act as a rear guard, moving in to control territory behind the conservative rebels’ offensive.

The military councils offer a vision of a democratic Syria and complain that the mujahedeen receive more support from donors abroad than the councils do, further increasing the Islamist fighters’ influence.

On Monday, it was clear that one of the Islamist groups, Jabhat al Nusra, has no plans to withdraw from Ras al Ayn. It also appears to have close operational links with the military council in Ras al Ayn, as well as Ghroba al Sham, the largest group of fighters in the city. Ghroba al Sham is considered by other rebel groups as having an ideology similar to Jabhat al Nusra’s. It operates outside the command of a military council.

At Jabhat al Nusra’s base in Ras al Ayn, the group’s leader apologized to a waiting journalist. He said he didn’t have time for an interview because he had to meet with PYD representatives to discuss a cease-fire agreement.

Hassan Abdullah, the commander of the local military council, said that meetings were taking place to create a civilian body to administer Ras al Ayn, whose residents largely fled when the fighting here began and have yet to return. There have been complaints of looting in the lawlessness that followed.

“What can we do? We are trapped between two sides,” asked one man who had returned to his home on Monday to check on it and said he planned to leave the city again before the end of the day. He declined to give his name.

As for rebel and Kurdish tensions, they are likely to get worse. The rebels suspect that the PYD is in fact a cover for continued control of the northeast by the government of President Bashar Assad, whose troops withdrew from the Kurdish areas four months ago, ceding control to the PYD.

But other Kurds have rallied to the PYD as the rebels have moved into Kurdish areas, including a group in Hasaka city, south of Ras al Ayn, that proposed setting up a “Free Kurdish Army” to act as a buffer between the PYD and the rebels. Now the men who intended to set up this new militia have said they would view any attack on the PYD as an attack on them.

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